US PatentsPat. No.Issue DatePatentee7,387,339Jun. 17, 2008Bykov et al.4,807,841Feb. 28, 1989Edstrom5,746,481May 5, 1998Obermeir4,099,697Jul. 11, 1978Von Shuckmann5,921,628Jul. 13, 1999Glockl9,060,612Jun. 23, 2015Lee9,010,867Apr. 21, 2015Martin et al.3,863,587Feb. 4, 1975Bosnich
Foreign PatentsPatent NumberIssue DatePatentee2988628 (EPO)Feb. 15, 2017Hugou et al.1997403 (EPO)Dec. 3, 2008Lenz et al.
As we spend more and more time using computers, smartphones, tablets, and other devices, we inevitably end up spending more time sitting. Because prolonged sitting is uncomfortable, furniture manufacturers have developed ergonomically contoured, supportive chairs intended to help us through the day. Though these chairs are well intentioned, the more time we sit passively with back support, the weaker our postural muscles become. Spending large amounts of time sitting passively tends to lead to postural degeneration and back pain. Furthermore, prolonged sitting has been correlated with increased risk of obesity, heart disease, cancer, and all-cause mortality.
Many furniture designers have become aware of the issues associated with passive sitting and have tried to solve the problem by creating devices that encourage people to sit actively. Though progress has been made, the sitting devices currently available have a variety of limitations.
One basic improvement over the traditional passive sitting device is to provide ways for the seat of the chair or stool to angle forward, opening up the hips to greater than 90 degrees in relation to the torso. Sitting with more open hips takes strain off the lower back, lengthens the hip flexors, and opens up the front of the body reducing compression of the user's internal organs. U.S. Pat. No. 7,387,339 to Bykov et al. (2008) and U.S. Pat. No. 4,807,841 to Edstrom (1989) allow for forward tilt while sitting. Though these sitting devices allow for a more open sitting angle, as conventional seats with backrests they discourage the user from actively supporting him or herself, and the user tends to slouch backward with extended sitting time.
A number of sitting devices have been made that open the angle of the user's pelvis and encourage active, dynamic sitting by allowing movement at the base of the central column. U.S. Pat. No. 5,746,481 to Obermeir (1998), U.S. Pat. No. 4,099,697 to Von Shuckmann (1978), and U.S. Pat. No. 5,921,628 to Glockl (1999) pivot angularly at or near the base of the central column allowing the user whole-body movement and encouraging the user to engage his or her legs while sitting. Though these types of sitting devices allow the user a wider range of whole-body movement than those described in the previous paragraph, they have two disadvantages. First, they rely on springs or elastic elements to bring the central shaft back to upright. Consequently, to whatever extent the user moves the seat and central column out of vertical alignment, his or her movement is met with greater mechanical resistance, reducing the need for the user to engage his or her core to remain upright. Secondly, the seats are rigidly set at ninety degrees to the central column allowing for limited freedom of movement of the user's pelvis and lumbar, thoracic, and cervical spine independent of the tilting of the central column.
U.S. Pat. No. 9,060,612 to Lee (2015) and U.S. Pat. No. 4,807,841 to Edstrom (1989) pivot just under the seat. These sitting devices afford the user an increased range of motion in the pelvis and lumbar, thoracic, and cervical spine front-to-back and side-to-side. However, because they include a base rigidly fixed at a right angle to the ground, they don't allow for the larger whole-body movements of the sitting devices mentioned in the previous paragraph.
European Patent Office patent 1997403 to Lenz et al. (2008) and U.S. Pat. No. 9,010,867 to Martin et al. (2015) afford the user a large range of motion by providing a base with a convex shape. These sitting devices don't rely on springs or other elastic mechanisms to return the central column and seat to upright. Instead, by virtue of their curved bases they come back to vertical alignment by means of gravity. Though this type of sitting device offers little resistance to off-axis tilt, because the base rolls in whatever direction the user leans, the result is that the user effectively has a solid support structure directly under where he or she sits requiring limited engagement of the legs and core muscles to remain upright.
European Patent Office patent 2988628 to Hugou et al. (2017) pivots freely at the base and allows for some pelvic, lumbar, and thoracic mobility by virtue of its small seat. However, the disadvantage of this sitting device is that it is unable to remain standing on its own, and it does not come back to vertical without the user picking up the device and placing it under him or her before sitting. Furthermore, the small sitting surface of the seat will tend to become uncomfortable with extended sitting.
Lastly, U.S. Pat. No. 3,863,587 to Bosnich (1975) pivots angularly between the seat and floor by means of a ball and socket joint, and a counterweight below the central pivot helps bring the seat to upright. Though this sitting device accommodates a wide range of motion and is self righting, it is intended for use by captains on ships to keep them upright while the boat pitches and rolls with the movement of the sea. To insure the user remains upright with as little effort as possible, the shaft below the ball and socket joint accommodates multiple weights.
To this end, U.S. Pat. No. 3,863,587 to Bosnich (1975) from the previous paragraph states, “Sufficient weights are added to more than counterbalance the weight of the occupant of the chair. More accurately, the weight of the occupant times the distance of the occupants [sic] center of gravity to the center of motion to the ball and socket joint must be less than the counterbalancing weights times the distance of their center of gravity to said center of motion. The occupant of the chair remains vertical with the horizon regardless of the roll and pitch of the ship.” Hence, the intended purpose of this sitting device is to reduce the activity needed by the user to remain upright. Furthermore, this sitting device has a backrest, demonstrating it is not intended to encourage active sitting.
In conclusion, insofar as I am aware, no sitting device formerly developed provides a sitting experience which:                1. allows the user to sit with a greater than ninety degree angle of the hips        2. requires the user to engage his or her legs and core muscles to remain upright,        3. allows for a wide range of movement in the user's pelvis and lumbar, thoracic, and cervical spine,        4. offers minimal resistance to the angular movement of the seat and central column,        5. returns the seat and central column to upright when not in use,        6. stands on its own, and        7. is intended to encourage active sitting.        